ABSTRACT
A simple colorimetric method for detection of isocarbophos was developed based on the enhanced peroxidase-like activity of hemin. Hemin could catalyze the oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2, which made TMB to lose one electron and caused reaction solution color changing from initial transparent to blue-green. Adding isocarbophos improved hemin affinity to substrates, which further enhanced peroxidase-like activity of hemin and made TMB to lose two electrons. The color of TMB solution was further changed from blue-green to yellow, and the degree of color change was proportional to the concentration of isocarbophos. Under the optimal conditions, the present analytical method for isocarbophos detection had a dynamic range from 2 μg/L to 100 μg/L with a detection limit of 1.2 μg/L (3σ). The selectivity assay demonstrated that other organophosphorus pesticides exhibited negligible interferences for isocarbophos detection. The application of the proposed method in the practical samples showed that the mean recovery of isocarbophos was in the range of 94.4％-113.0％, thus it could be widely applied to rapidly and sensitively detect isocarbophos in the agricultural products.
